1. Field of the Invention
The present invention relates to a rotary drive device for inspecting blades of a turbo-fan engine.
2. Description of the Prior Art
Turbo-fan Engines, particularly those for aircraft require periodic inspection of compressor blades or fan and low-pressure turbine blades since a damage or a failure in such essential components of the engine may lead to a serious accident.
Although there are known various types, the turbo-fan engine essentially comprises a high-pressure compressor, a low-pressure compressor and related turbines, wherein the high-pressure compressor and the corresponding turbine are linked with a drive mechanism through gears while the low-pressure compressor or fan and the corresponding turbine are not linked with said drive mechanism and are freely rotatable by air stream. Consequently the blades of the high-pressure compressor and the corresponding turbine can be visually inspected by rotating said compressor and turbine externally by said drive mechanism at a suitable speed, but the low-pressure compressor or fan and the corresponding turbine cannot be rotated externally due to the lack of gear linkage as explained above and have to be manually rotated gradually for the blade inspection. Although such manual rotation of the fan blades is relatively easy in an engine in which the fan blades are easily accessibly positioned in the vicinity of the front air inlet of the rocket-shaped fan case housing the turbo-fan engine, an engine having deep blade position requires the inspector to lie down in order to make such access, and the operation of blade inspection with manual rotation of the fan blades in such lying posture is quite toilsome for the inspector.